см. Введение

Контрольная работа №3 для специальностей 1201. 1806.2101

Вариант 5

I. Закончить предложения:

1. An ammeter is an instrument used for measuring an electric current in amperes.

II. Перевести словосочетания:

1. combustion camera

III. Правильно определите форму слов с -ing и переведите текст.

The diagram shows the coil ABCD rotating between the poles N. and S. in a clock wise direction.

IV. переведите производные:

Charge,

V. Переведите текст

The motor circuit comprises DC motor Д, line contactor КЛ, acceleration contactor КУ, differential relay P, thermal relay TPA and resistors.

Starting the motor is as follows: in closing switch circuit 2-3, the mains voltage is supplied to circuit 16-3 of line contactor КЛ coil, and the contactor operates. Its main contacts 13-15 connect to the circuit motor parallel winding Н1Д, generator excitation winding ВГ (through series resistor), motor armature circuit (through starting resistor CI). Now the armature starts relating.

Auxiliary contacts 1-35 and 3-20 of the line contactor КЛ close at the same time as its main contact does. Circuit 35-14 of the differential relay P holding coil У1 is switched in parallel with starting resistor CI. Circuit 14-20 of the operating coil Pi of the same relay is switched in parallel with the motor armature circuit.

With the motor armature speed increase, the voltages across the operating and holding coils of relay P increase and decrease, respectively, due to the increase of the armatures counter-emf.

At a certain speed of the armature rotation, the operating coil voltage reaches a value at which differential relay P operates and its contact 18-35 prepares, on closing, a circuit to supply acceleration contactor КУ coil (for details of the differential relay principle of operation refer to the subsection "The P-30 electromagnetic differential relay").

Contactor КУ operates and shunts, by its main contact 13 - 14, starting resistor CI. At the same time, auxiliary contact 23-25 of contactor КУ in the generator staler auxiliary winding will also close.

The motor starting will come to an end when the armature rotational speed reaches a steady-slate value.

Stopping the motor is done with the switch. With this, circuit 2-3 of the switch becomes open to deenergize the КЛ line contactor coil circuit. Main contacts 13-15 of the contactor open and switch the motor off the mains while auxiliary contacts I-35 and 3-20 switch off acceleration contactor КУ circuit and open the differential relay P circuit. The elements of these circuits assume the initial position (the pre-start one).

The motor protection. At overload and short-circuit, the motor is switched off the mains automatically with the help of the TPA relay whose heating element 1-15 is brought into the motor supply circuit while contact 1-16 is brought into the circuit of the КЛ line contactor coil. When the relay picks up its contact 1 - 16 breaks and deenergizes the line contactor coil circuit thus switching the motor off the mains. Unless the overload or short-circuit are eliminated by the moment the contact resets, the relay operates once more on the contact resetting and the motor is switched off the mains. The relay will keep switching the motor on and off until the trouble is eliminated. The control circuit is protected against short-circuit by fuses ПР.

нет

Примечаний нет.